An organic electroluminescence (“electroluminescence” will be occasionally referred to as “EL”, hereinafter) device is a spontaneous light emitting device which utilizes the phenomenon that a fluorescent substance emits light by energy of recombination of holes injected from an anode and electrons injected from a cathode when an electric field is applied. Since an organic EL device of the laminate type driven under a low electric voltage was reported by C. W. Tang et al. of Eastman Kodak Company (C. W. Tang and S. A. Vanslyke, Applied Physics Letters, Volume 51, Page 913, 1987), many studies have been conducted on organic EL devices using organic materials as the constituting materials. Tang et al. used tris(8-quinolinolato)aluminum for the light emitting layer and a triphenyldiamine derivative for the hole transporting layer. Advantages of the laminate structure are that the efficiency of hole injection into the light emitting layer can be increased, that the efficiency of forming excitons which are formed by blocking and recombining electrons injected from the cathode can be increased, and that the excitons formed in the light emitting layer can be confined. As the structure of the organic EL device, a two-layered structure having a hole transporting (injecting) layer and an electron transporting and light emitting layer and a three-layered structure having a hole transporting (injecting) layer, a light emitting layer and an electron transporting (injecting) layer are well known. To increase the efficiency of recombination of injected holes and electrons in the devices of the laminate type, the structure of the device and the process for forming the device have been studied.
Conventionally, aromatic diamine derivatives described in Patent Document 1 below and aromatic diamine derivatives with fused rings described in Patent Document 2 below have been known as hole transporting materials for the organic EL devices.
As improved compounds, Patent Documents 3 to 5 disclose arylamine-based compounds containing carbazole, which are employed as hole transporting materials. Further, Patent Document 6 discloses an arylamine-based compound having 3-position-substituted carbazole {e.g. Compound (A) below}, which is employed as a hole injecting material. Although some improvements in an efficiency of light emission or so are achieved in the devices employing those compounds into a hole injecting layer or a hole transporting layer, the efficiency of light emission is not sufficient yet and further enhancement of the efficiency of light emission was required.
Furthermore, although Patent Document 7 discloses arylamine-based compounds having 3-position substituted carbazole {e.g. Compound (B) below}, they are employed as a phosphorescent host material, without reporting any embodiment of employing them as a hole injecting material or a hole transporting material in the past.
Moreover, although Patent Document 8 discloses compounds wherein 3-position substituted carbazole bonds to amine via a phenylene group, there were problems that the compounds have an elevated vapor deposition temperature and that the efficiency of light emission was small. There was a shortcoming in Compound 24 disclosed in Patent Document 9 that it had a short device lifetime. Further, there was also a shortcoming in Compound 40 disclosed in Patent Document 9 that it had an elevated vapor deposition temperature.
    Patent Document 1: U.S. Pat. No. 4,720,432    Patent Document 2: U.S. Pat. No. 5,061,569    Patent Document 3: U.S. Pat. No. 6,242,115    Patent Document 4: JP 11-144873A    Patent Document 5: JP 2000-302756A    Patent Document 6: JP 2006-151979A    Patent Document 7: JP 2005-290000A    Patent Document 8: JP 2003-133075A    Patent Document 9: JP 2004-079265A